1. Field of the Invention
This invention pertains generally to farm and construction tools, and more particularly to an improved manual stake or post extraction device.
2. Description of the Background Art
In commercial and residential construction projects, stakes made of metal or wood are used in many applications. Typically, a foundation or footing is constructed by pouring concrete into forms that are properly positioned by stakes securely embedded in the ground. Stakes may also be used to establish boundary lines or markers at a construction site. In addition, temporary barriers and fencing are primarily created by driving metal posts into the ground.
Disassembly of concrete forms after the concrete has solidified, as well as the removal of temporary barriers, ultimately requires the removal of the supporting stakes or posts. However, the removal of a post or stake can be quite difficult. Attempts to dislodge a wooden stake or post by hand can often result in the post breaking and leaving a portion of the post in the ground. Removal of the broken pieces requires digging, thereby disrupting the soil surrounding the formed concrete and potentially compromising the concrete. Aggressive attempts to remove a post or stake without mechanical assistance may also lead to injury. Thus, breakage of the stake or post is undesirable because it results in additional work and lost time for the workman and possible damage to concrete structures.
Posts and stakes come in a variety of cross-sectional shapes and diameters. The cross-section may be round, square, rectangular or "T"0 shaped. Many post pulling tools found in the prior art are limited to removing posts with a particular cross sectional shape. For example, U.S. Pat. No. 5,224,687 issued to Geckler discloses a device for removing a post with a generally "T"0 shaped cross-section which utilizes an engagement plate and a conventional jack. The Geckler device would not be suitable for removing square, round or rectangular stakes or posts. Similarly, the post puller described in U.S. Pat. No. 5,186,437 issued to Scott also uses an engagement plate adapted to receive a square post and has similar limitations. Likewise, the device described in U.S. Pat. No. 5,052,659 issued to Bates in 1991 is limited to removing stakes with a round cross-section within a specific range of circumferences. These representative prior art devices are limited to removing posts with a certain cross sectional shape and therefore cannot be used for removing stakes with differing cross-sectional shapes or sizes.
Another deficiency in existing prior art pullers is that the engagement plate must be placed over the top of the post or stake and brought down to the proper position before extraction. This requires the user to remove nails or other obstructions before the device can be used. Such a requirement increases the overall time and work required to extract each stake. For example, the post puller disclosed in U.S. Pat. No. 5,464,192 to Burnham requires the post to be placed between two "gripper bars"0 in the head of the device. During use, the entire Burnham apparatus must be lifted up and over the top of each post.
Yet another deficiency in prior art devices is that such devices cannot be used to pull stakes that abut a board or concrete form. For example, the post puller disclosed in U.S. Pat. No. 5,833,215 to Vandenburg requires the engaging head to completely surround the post limiting the use of the apparatus to free standing posts. Likewise, the stake pulling apparatus of U.S. Pat. No. 5,597,151 issued to Duncan requires the stake to be surrounded by the stake engagement head and is therefore limited to removal of free standing stakes.
Accordingly, there is a need for a for a mechanical device to remove a stake that abuts a vertical object, that can remove stakes of varying cross-sectional sizes and shapes; and can quickly engage the stake without requiring excessive activity by the user.